This invention relates to a machine and method for continuously forming a series of filled pouches from a continuous web of flexible material and packing the pouches in a carton. The pouches are commonly used to package a wide variety of products such as sugar, sweeteners, drink mixes, soup mixes and the like in individual or small serving sizes. Liquid products as well as dry products can be packaged in this type of pouch. A variety of web materials can be used such as paper or foil which are relatively stiff and non-extensible or oriented polypropylene or polyester which are somewhat soft and extensible. The web may be coated on at least one side with a heat sealable material such as polyethylene which is suitable for forming heat seals.
An example of a prior art pouch machine is shown in U.S. Pat. No. 3,453,799, the disclosure of which is incorporated herein by reference. The typical pouch machine includes a base supporting various components including an unwind stand for supporting a roll of pouch material. The web is unwound in a generally horizontal plane and advanced to a plow which folds the web generally in half about a longitudinal fold line. The fold line is disposed at the bottom of the web which then assumes a V-shape with front and back panels on either side of the fold in a substantially vertical plane.
The folded web is then pulled around a rotary vertical sealer which has a series of vertically extending circumferentially spaced heated lands on its periphery which are provided to form longitudinally spaced, vertically extending heat seals in the web. This sealing process forms pockets or pouches between the front and back panels of the web. The tops of the pouches remain open for filling at a filling wheel which opens the pouches and inserts the desired quantity of the product being packaged. Thereafter, the web is moved to a top sealer which seals the tops. The filled and sealed pouches are transferred to a knife which severs the pouches into what will be referred to herein as pouch units. Pouch units may be either single, individual pouches, or related groups of individual pouches, or groups of pouches that are not severed from one another but instead have perforations between them, e.g., multi-flavor packs.
The filling process naturally results in a greater portion of the product resting in the bottom portion of the pouch. Accordingly, the bottom of the pouch is often thicker than the top. This uneven thickness may create problems when many individual pouches are stacked adjacent one another or one on top of the other in a carton or other container. The pouches have a wedge-like shape and will not lay or stand in a uniform stack. If the pouches are laid flat, the stack quickly becomes out of balance, with the upper pouches tending to fall or slide off the stack. While it is possible to compensate for uneven thickness by turning half the pouches 180 degrees, extra equipment is required to do so. These handling difficulties increase the time and cost of packing pouches in cartons and make it virtually impossible to gather a complete stack outside the carton and then transfer that stack all at once into the carton. Instead, the carton must be filled gradually with pouch units as they come out of the knife.
One problem with loading pouch units seriatim into cartons is the need to alter the point where pouches are placed as the carton fills up. That is, once a conveyor or other device places a pouch in the carton, the succeeding pouch cannot follow the first pouch into the same space because if it were to do so the second pouch would collide with the first one. The second pouch has to be placed next to the first pouch. Thus, the target zone for the placement mechanism changes with every pouch. This moving target problem cannot be circumvented by inserting pouches at one end of the carton and letting them fall onto a stack built up at the opposite end of the carton. The reason is that the pouches will not reliably fall any appreciable distance without turning, tilting, twisting or canting within the carton. Instead of building up a neat stack with each pouch lying or standing flat against its neighbor, such a free falling system would lead to chaos wherein the pouches are oriented crazily in unknown fashion within the container.
There have been efforts to solve the moving target problem by moving the conveyor which places the pouches in the carton, i.e., moving the discharge point of the conveyor. This greatly complicates the conveyor's structure and fails to address the need to get a filled carton out of the way for the next, empty one.